scholarly journals Numerical Study on the Influence of Shaping Air Holes on Atomization Performance in Pneumatic Atomizers

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 410 ◽  
Author(s):  
Wentao Li ◽  
Lijuan Qian ◽  
Shaobo Song ◽  
Xiaokai Zhong
Keyword(s):  
Droplet Size ◽  
Numerical Study ◽  
Droplet Size Distribution ◽  
Target Surface ◽  
Central Pressure ◽  
Gas Velocity ◽  
Two Phase ◽  
Atomization Performance ◽  
The Relationship ◽  
Spraying Process

In pneumatic atomizers, the shaping air holes play an important role in the spraying system. The pressure and intersection of shaping air holes are the two most important parameters in engineering. In this paper, the Euler–Lagrangian method is used to describe the two-phase spray flow. The spraying process of the pneumatic nozzle is simulated numerically, and the experiment is designed to verify this simulation. By setting different air pressures and distances between the intersection and the paint hole, target surface pressure and droplet size distribution are investigated in detail, in order to explore the relationship between shaping air holes in pneumatic nozzles and overspray. From the results of the numerical simulation, it is found that an increase in the distance between the intersection and the paint hole increases the gas velocity at the central axis of the nozzle and the central pressure of the target surface, the droplet size becomes larger, and the distribution of droplets is more concentrated on the target surface, which easily leads to overspray. With the increase in the pressure of the shaping air holes, the central pressure of the target surface decreases, and the ovality of the spraying pattern on the target surface increases.

scholarly journals Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1233
Author(s):  
Umair Jamil Ur Rahman ◽  
Artur Krzysztof Pozarlik ◽  
Thomas Tourneur ◽  
Axel de Broqueville ◽  
Juray De Wilde ◽  
...  
Keyword(s):  
Spray Drying ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Three Dimensional ◽  
Droplet Size Distribution ◽  
Vortex Chamber ◽  
Temperature Pattern ◽  
Multiphase Model ◽  
Drying Technology

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 µm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 µm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology.

Numerical Simulation of Black Liquor Spray Characteristics

2002 ◽  
Author(s):  
Thomas D. Foust ◽  
Kurt D. Hamman ◽  
Brent A. Detering
Keyword(s):  
Droplet Size ◽  
Volume Fraction ◽  
Numerical Study ◽  
Black Liquor ◽  
Flow Distribution ◽  
Physical Models ◽  
Spray Characteristics ◽  
Two Phase ◽  
Vof Model ◽  
Sheet Breakup

The performance and capacity of Kraft recovery boilers is sensitive to black liquor velocity, droplet size and flow distribution in the furnace. Studies have shown that controlling droplet size and flow distribution improves boiler efficiency while allowing increased flight drying and devolatilization, and decreased carryover. The purpose of this study is to develop a robust two-phase numerical model to predict black liquor splashplate nozzle spray characteristics. A three-dimensional time dependent numerical study of black liquor sheet formation and sheet breakup is described. The volume of fluid (VOF) model is used to simulate flow through the splashplate nozzle up to initial sheet breakup and droplet formation. The VOF model solves the conservation equations of volume fraction and momentum utilizing the finite volume technique. Black liquor velocity, droplet size and flow distribution over a range of operating parameters are simulated using scaled physical models of splashplate nozzles. The VOF model is compared to results from a flow visualization experiment and experimental data found in the literature. The details of the simulation and experimental results are presented.

Experimental Study of Leidenfrost Phenomena at Hot Sprayed Surface

2003 ◽  
Author(s):  
M. Raudensky´ ◽  
J. Horsky´ ◽  
V. Dumek ◽  
P. Kotrba´cˇek
Keyword(s):  
Experimental Study ◽  
Droplet Size ◽  
Impinging Jets ◽  
Spray Parameters ◽  
Surface Cooling ◽  
Two Phase ◽  
Coefficient Distribution ◽  
Flow Experiment ◽  
Leidenfrost Temperature ◽  
The Relationship

An experimental study was prepared to find the relationship between Leidenfrost temperature and droplet size and velocity of impinging jets. The study is done for the case of steel surface cooling with two-phase nozzles. The sprayed surface moves under the spray at a velocity of 1 m/min. Cooling experiments were done for initial temperature of 1250°C. Thermal experiments are transient: internal temperature is measured and surface temperature and heat transfer coefficient distribution is computed by the inverse task. Droplet size and velocity of the impinging jet was modified by setting water and air pressures at the input of the nozzle. Spray parameters for each pressure combination was measured using a laser-doppler anemometer. The paper shows the results of the thermal and fluid flow experiment and the correlation between Leidenfrost temperature and flow parameters.The application of obtained results is expected for high temperature cooling especially in continuous casting.

Study on atomization particle size characteristics of two-phase flow nozzle

2021 ◽  
pp. 1-12
Author(s):  
Haoqi Lilan ◽  
Junbin Qian ◽  
Nan Pan
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Droplet Size ◽  
High Speed ◽  
Droplet Size Distribution ◽  
Average Diameter ◽  
Spray Atomization ◽  
Two Phase ◽  
Nozzle Pressure ◽  
Local Observation

Nozzle spray atomization is widely used in industrial and agricultural production processes and is a very complicated physical change. The spray atomization of the nozzle is a process in which the droplets are continuously broken into finer particles under the action of force, in order to study the effect of nozzle atomization, that is, droplet size distribution characteristics. The experimental average mathematical model of droplet size distribution was established by introducing the average diameter of Sutter (SMD). The droplet size distribution in the atomization field of the nozzle is studied by simulation. In the experimental study, the high-speed camera, external mixing air atomizing nozzle platform experimental device and image processing were used, and the atomization field was divided into multiple observation areas. Through the measurement of several local observation areas, the droplet size distribution of the whole atomization field is constructed. It provides a reference for the study of the atomization field of the nozzle and a basis for the intuitive understanding of the droplet size distribution in the atomization field of the nozzle. The effective atomization area of the nozzle atomization was selected to study the influence of the liquid flow rate, the liquid temperature and the nozzle pressure on the atomized particle size distribution of the externally mixed atomizing nozzle. The internal law is obtained, which provides a basis and reference for effectively controlling the atomization effect in the atomization field.

Modeling Subsurface Dispersant Applications for Response Planning and Preparation

2014 ◽  
Vol 2014 (1) ◽  
pp. 933-948 ◽  
Author(s):  
Deborah Crowley ◽  
Daniel Mendelsohn ◽  
Nicole Whittier Mulanaphy ◽  
Zhengkai Li ◽  
Malcolm Spaulding
Keyword(s):  
Interfacial Tension ◽  
Water Column ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Relative Volume ◽  
Modeling Tools ◽  
Droplet Sizes ◽  
Oil Water ◽  
The Relationship

ABSTRACT The increase in oil and gas development activity at increasing water depths has highlighted the need for modeling tools to evaluate the unique aspects of accidental deepwater releases, one aspect being the need to assess the impact of subsurface dispersant application to a deepwater blowout. In response to this need, the effect of subsurface dispersant application has been implemented within RPS ASA's blowout model OILMAPDeep. OILMAPDeep was developed to simulate deepwater blowout releases; it predicts the evolution and characteristics of the subsurface plume and estimates the oil droplet size distribution associated with the release. The droplet size distribution dictates the vertical transport of oil within the water column, and impacts the relative volume anticipated to either surface or remain trapped in the water column. Droplet sizes are primarily a function of the energy of the release and the oil-water interfacial tension. The energy of the release is characterized by a reference velocity, typically the exit velocity, and the oil-water interfacial tension as a function of the oil properties. Dispersants mixed with oil reduce the oil-water interfacial tension, which in turn reduces the droplet sizes associated with treated releases serving to delay or eliminate surfacing oil. The present model implementation takes advantage of recent studies that have quantitatively assessed the relationship between the dispersant to oil ratio and surface tension. Here we present a background of the OILMAPDeep module, the governing physical processes of droplet formation, and the relationship between dispersant-to-oil ratio (DOR) and droplet size formation as characterized in the model. A description of the model implementation including model inputs and outputs are provided. Furthermore a set of scenarios are presented that demonstrate the model's capabilities for planning and preparing response activities in the event of a potential oil well blowout. This paper shows how the implementation of subsurface dispersant application within OILMAPDeep provides an effective means of evaluating potential response activities associated with subsurface dispersant application to a deepwater blowout. This includes evaluating the effect of subsurface dispersant application on droplet size distribution, and the ultimate impact on the timing, location and the relative volume of surfacing oil.

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